Wire wound resistance and method for making same



INVENTORS C. HUETTEN ET AL Filed May 22, 1953 A FIGZ Q \\\\\\\\\\\YII'IIIIIIIIIIIIIIIIA ISISLQISLSXS CLARENCE HUETTEN BY HOWARD R. REEVEJune 28, I955 WIRE WOUND RESISTANCE AND METHOD FOR MAKING SAME UnitedStates Patent 2,712,648 "ti IRE WJUND RESISTANQE AND METHOD FOR MAKINGSAME Clarence ll-hictten and Howard R. Reeve, Indianapolis,

Ind, assignors to the United States of America as represented by theSecretary of the Army Application May 22, 1953, Serial No. 356,736

6 Claims. (Cl. 20163) This invention relates to electrical resistors andmore particularly to terminals for wire wound resistance devices and amethod of making such devices.

The use of wire wound variable resistance devices comprising anarcuately-shaped core wound with resistance wire over which a movablecontact arm travels is well known in the art. Such devices usually havemetal terminals clipped to the ends of the resistance winding, therebylimiting the travel of he contacting The present invention represents animprovement in such wire wound resistance devices.

An important obiect of the present invention is to pro vide a wire woundresistance device having movable con tacts touching one of its faces,said contacts being free to travel over the entire face of said device.

Another important object is to provide a wire wound resistance devicewhich utilizes terminal inserts in its core, thereby maintaining one ofits winding faces entirely free for contactors.

A further object is to provide a wire wound resistance device that isfree from abrupt surface changes along the entire length of a face ofthe winding.

A still further object is to provide a wire wound resistance devicehaving terminal inserts that prevent mechanical damage to the resistancewire when stresses are applied to said inserts.

Other objects and advantages of this invention will become apparentduring the course of the following discussion.

In the accompanying drawing:

Fig. l is a plan View of the invention pa tially assembled;

Fig. 2 is an expanded, cross-sectional view of Fig. 1, taken at line 22before the elements have been fused; and

Pig. 3 shows the structure of Fig. 2 after the elements have been fused.

Fig. 1 shows a core 1, which may be made of any conventional dielectricmaterial. ireferably, as shown in Figs. 2 and 3, the core It comprises adielectric with fabric imbedded therein. in Pig. 1 is shown the fabricgrain 19 and the core is shown as being cut on a 45 bias with thisgrain. By cutting the core on a 45 bias to the grain 19 of the fabric,it is possible to bend the core around a small radius.

Fig. 1 further shows a keyhole-shaped slot 17 disposed on the left sideof the core 1. A similar slot is disposed on the right side of core 1,but is hidden by a disc 9. A spade-shaped insert 11, made up of a shankportion 15 and a blade portion 13, has the same configuration as slot 17and is inserted in the slot on the right side of core 1. A similarinsert, not shown, is inserted in slot 17. A resistance wire is woundabout the core 1 along substantially the entire length of said core, asindicated by dashed lines 2i. The disc 9 is positioned directly over theblade portion 13 of insert 11.

Fig. 2 is an expanded cross-sectional view of Fig. 1, taken along line22, and provides a more detailed view of the present invention. T heinsert ll. has a silver solder overlay '7 on its blade portion 13, andis inserted in the slot of core 1. When resistance wire 3 is wound aboutthe core, it also incloses blade portion 13. The metallic disc 9, havinga silver solder overlay 5 on one face thereof, is then placed on wire 3,so that overlay 5 is in contact with wire 3 and is in juxtaposition withoverlay By applying two electrodes of a resistance soldering unitsistance wire wound on the co at points marked A and B, the solderoverlays 5 and '7 are fused together.

As shown in Fig. 3, when the overlays 5 and 7 are fused together, asolder joint 23 is formed so that a portion of winding 3 is nowcompletely contained and permanently connected between blade portion 13of insert 11 and disc 9". Thus, a. wire wound resistance device is madethat presits a face permitting an extended range of travel for contactstouching it. Also, the device is mechanically strong, preventing thewire from being broken due to stresses on the insert.

While there has been described what is, at present, con- .ered to be thepreferred embodiment of this invention, will be obvious that variouschan es and modifications be made therein without departing from theinventive conce,.r herein discloset.

i /hat is claimed is:

l. electrical resistance device comprising a dielece. a metal ic insertdisposed wit in and interlocked with s-aio core, resistance wire woundabout said core and cnclosin said insert and means comprising a metallicdisc l'iaving a solder overlay on one side thereof for bonding said wirebetween said disc and insert.

2. A resistance device as set forth in claim 1, wherein said core hastherein an irregularly-shaped slot disposed at one end thereof, saidslot having a first portion narrower than a second portion, said firstportion being at the edge of said core, said insert being disposedwithin said slot.

3. A resistance device as set forth in claim 2, wherein said insert andslo have the same configurations.

4. An electrical resistance device comprising, a relatively thindielectric core havin at least one keyholeshaped slot at one endthereof, said slot being positioned at substantially the center of theWidth of said core, a spade-shaped metallic terminal insert having asilver solder overlay on its blade, said blade and a part of the shankof said keyhole-shaped insert bein disposed within said slot, the shapeof the portion of said insert within said slot being the same as theshape of said slot, said insert and said core being interlocked, aresistance wire tightly Wound about said core from one end thereof tothe other end and enclosing the blade of said insert, a metallic dischaving a silver solder overlay on one side thereof which is fused to theoverlay of said insert for completely containing and permanentlyconnecting a portion of said wire between said insert and said disc.

5. An electrical resistance device as set forth in claim 4, wherein saidcore comprises a dielectric having a fabric imbedded therei said corebeing cut on a 45 bias to the a grain of said fabric, whereby said coremay be bent about small radii.

6. A process for producing an electrical resisetance device includingdielectric core, netallic terminals, and recomprising the steps of,interlocking a ke hole-shaped metallic terminal insert having a silversolder overlay on its blade portion with a relatively thin,rectangularly-shaped dielectric core having at least one spade-shapedslot at one end thereof to receive said insert, said slot beingsubstantially at the center of the width of said core and complementingthe portier. of said insert tliercwithin, tightly u'iding resistancewire about. said core from one end thereof to the other and enclosingsaid insert, and fusing a metallic disc having a silver solder overlayon one side thereof to the overlay of said insert to completely containand permanently connect a portion of said wire between said insert andsaid disc.

1 Nov. 3, 1914 rlo z June 20, 1939

1. AN ELECTRICAL RESISTANCE DEVICE COMPRISING A DIELECTRIC CORE, AMETALLIC INSERT DISPOSED WITHIN AND INTERLOCKED WITH SAID CORE,RESISTANCE WIRE WOUND ABOUT SAID CORE AND ENCLOSING SAID INERT AND MEANSCOMPRISING A METALLIC DISC HAVING A SOLDER OVERLAY ON ONE SIDE THEREOFFOR BONDING SAID WIRE BETWEEN SAID DISC AND SAID INSERT.